1. Field of the Invention
This invention relates to a disc cartridge for housing a disc-shaped recording medium, such as an optical disc or a magneto-optical disc, loaded on a recording and/or reproducing apparatus.
2. Description of the Related Art
There has hitherto been used a disc cartridge housing an optical disc, a magneto-optical disc or a magnetic disc and which is loaded therewith on a recording and/or reproducing apparatus.
As this type of the disc cartridge, there is known such a device described in the U.S. Pat. Nos. 4,510,546 and 4,876,619.
With the disc cartridge described in these publications, a disc as a recording medium is rotationally housed within a main cartridge body unit which is rectangular in shape. The main cartridge body unit has a recording and/or reproducing opening for allowing a portion of the housed magnetic disc to be exposed to outside across the inner and outer rims of the disc. This main cartridge body unit carries a shutter member, rectangular in cross-section, adapted to be moved along the front side of the main cartridge body unit for opening/closing the recording and/or reproducing opening.
As a disc cartridge housing a disc as an information recording medium, there is known such a one as described in the U.S. Pat. No. 4,614,990.
The disc cartridge described in ""990 patent has a rectangular main cartridge body unit within which is rotatably mounted a disc as an information recording medium. The main cartridge body unit is formed with a recording and/or reproducing opening for allowing part of the disc housed therein to be exposed to outside across the inner and outer rims of the disc. On the main cartridge body unit is mounted a rectangular shutter member moved along the front surface of the main cartridge body unit for opening/closing the recording and/or reproducing opening.
As a disc cartridge housing a disc as an information recording medium, a known example is disclosed in U.S. Pat. No. 5,570,252. The disc cartridge disclosed in the ""252 patent has an opening in a lateral surface of the main cartridge body unit. The magnetic head is introduced via this opening into the inside of the disc cartridge into sliding contact with the signal recording region of the magnetic disc. In the ""252 cartridge, the shutter member adapted for opening/closing the opening is mounted for performing movement along a lateral side of the main cartridge body unit.
Meanwhile, in the disc cartridges disclosed in U.S. Pat. Nos. 4,510,546 and 4,876,619, the recording and/or reproducing opening is formed centrally of the width of the main cartridge body unit, and a shutter member for opening/closing this opening is mounted for movement along the front surface of the main cartridge body unit as a ersult, it is difficult to provide an opening larger in size than the main cartridge body unit.
Also, in the disc cartridge disclosed in the U.S. Pat. No. 4,614,990, the disc cartridge is inserted into the recording and/or reproducing apparatus, with the movement direction of the shutter member as the inserting direction. Thus, the recording and/or reproducing mechanism, such as an optical pickup device, arranged on the recording and/or reproducing apparatus employing this disc cartridge, is moved in a direction perpendicular to the disc cartridge inserting direction to scan the recording medium, so that, when the recording and/or reproducing mechanism scans the outer periphery of the recording medium, the recording and/or reproducing mechanism is partially protruded from the area of loading of the disc cartridge, with the result that the recording and/or reproducing apparatus is increased in width.
In the disc cartridge disclosed in the U.S. Pat. No. 5,570,252, in which the magnetic head is inserted into the inside of the main cartridge body unit via the narrow opening provided in the lateral side of the main cartridge body unit, there are imposed limitations on the recording and/or reproducing mechanism used. Such disc cartridge is extremely difficult to apply to an optical disc used in an optical pickup device. Moreover, the shutter member is configured for opening/closing the opening which is narrow in width and longer in length than in width, the shutter member is also narrow in width and longer in length to render it difficult to realize stable movement of the shutter member.
It is therefore an object of the present invention to provide a disc cartridge in which there is provided a recording and/or reproducing opening larger in size than the main cartridge body unit housing the disc-shaped recording medium to enable a large-sized recording and/or reproducing opening to be used, and in which there is also provided a shutter mechanism that is able to positively close the large-sized opening.
It is another object of the present invention to provide a disc cartridge in which the opening provided in the main cartridge body unit can be reliably closed to protect the disc-shaped recording medium housed in the main cartridge body unit.
It is still another object of the present invention to provide a disc cartridge in which the recording and/or reproducing mechanism is arranged within the range of the extent of the disc cartridge to render it possible to reduce the width of the recording and/or reproducing apparatus.
It is yet another object of the present invention to provide a disc cartridge in which insertion thereof into the recording and/or reproducing apparatus can be easily distinguished and which can be reliably loaded on the recording and/or reproducing apparatus.
In view of the above objects, the present invention provides a disc cartridge for housing a disc-shaped recording medium adapted for recording information signals thereon, including a disc-shaped recording medium, a main cartridge body unit having a circular medium housing section for rotationally housing the disc-shaped recording medium and an opening for allowing at least a portion of the disc-shaped recording medium to be exposed to outside, and first and second shutter members rotated along the major surface of the main cartridge body unit within the regions of the circular medium housing section foropening/closing the opening. The first shutter member is supported for rotation along the circular medium housing section provided in the main cartridge body unit. The second shutter member is supported by the main cartridge body unit for rotation in association with the rotation of the first shutter member. The second shutter member is intimately contacted with a lateral side of the first shutter member to cover the opening when the first shutter member has been moved to a first position overlying the opening. The second shutter member is rotated along with the first shutter member to a position exposing the opening when the first shutter member has been rotated to a second posit ion of exposing the opening.
Since the opening provided in the main cartridge body unit is opened/closed by the first and second shutter members moved along the major surface of the main cartridge body unit, the opening can be larger in size than the main cartridge body unit, and the opening, thus increased in size, can be opened/closed positively.
Since the second shutter member has its portion engaged and held by an engagement holding portion provided on the first shutter member, so that the second shutter member is rotated in association with rotation of the first shutter member, other is no necessity of providing an independent mechanism for causing movement of the second shutter member, and hence the shutter mechanism can be simplified in structure even though there are provided plural shutter members.
The present invention also provides a disc cartridge including a main cartridge body unit combined from an upper half cartridge and a lower half cartridge abutted and connected to each other and within which a disc-shaped recording medium is housed rotationally, including a recording and/or reproducing opening provided in the main cartridge body unit for exposing a signal recording region of the disc-shaped recording medium at least across inner and outer rims thereof, a driving opening provided in the main cartridge body unit to permit entrance of rotating driving means for rotationally driving the disc-shaped recording medium, and a shutter mechanism for opening/closing the recording and/or reproducing opening and the driving opening. A lateral surface of the main cartridge body unit is formed as a continuous arcuate surface having a swollen-out center portion. Since a lateral surface of the main cartridge body unit is arcuate, the direction of insertion into the recording and/or reproducing apparatus can be discerned easily to prevent mistaken insertion to facilitate the prompt insertion into the recording and/or reproducing apparatus.
The present invention also provides a disc cartridge housing therein a disc-shaped recording medium on which are recorded information signals, including a cartridge body unit having a substantially circular recording medium housing section for rotationally housing a disc-shaped recording medium approximately 120 mm in diameter and also having an opening for exposing at least a portion of the disc-shaped recording medium housed in the recording medium housing section across inner and outer rims of the disc-shaped recording medium to outside, and a shutter member moved along a major surface of the cartridge for opening/clogging the opening. The shutter member has its one end supported for movement in a groove formed along the outer peripheral surface of an arcuate housing section forming wall, this movement causing the opening/closure of the opening.
Since the shutter member is moved about the portion thereof supported outwardly of the recording medium housing section as center, there is no necessity of providing a shutter member supporting portion within the region of the recording medium housing section, it is possible to reduce the thickness of the main cartridge body unit.
Other objects and advantages of the present invention will become apparent from the following detailed description of the preferred embodiments and the claims.